Abstract
5-Hydroxytraptamine (5-HT) is a precursor and a putative modulator for melatonin synthesis in mammalian pinealocytes. 5-HT is present in organelles distinct from L-glutamate containing synaptic-like microvesicles as well as in the cytoplasm of pinealocytes, and is secreted upon stimulation by norepinephrine (NE) to enhance serotonin N-acetyltransferase activity via the 5-HT2 receptor. However, the mechanism underlying the secretion of 5-HT from pinealocytes is unknown. In this study, we show that NE-evoked release of 5-HT is largely dependent on Ca2+ in rat pinealocytes in culture. Omission of Ca2+ from the medium and incubation of pineal cells with EGTA-tetraacetoxymethyl-ester inhibited by 59 and 97% the NE-evoked 5-HT release, respectively. Phenylephrine also triggered the Ca2+-dependent release of 5-HT, which was blocked by phentolamine, an α antagonist, but not by propranolol, a β antagonist. Botulinum neurotoxin type E cleaved 25 kDa synaptosomal-associated protein and inhibited by 50% of the NE-evoked 5-HT release. Bafilomycin Al, an inhibitor of vacuolar H+-ATPase, and reserpine and tetrabenazine, inhibitors of vesicular monoamine transporter, all decreased the storage of vesicular 5-HT followed by inhibition of the NE-evoked 5-HT release. Agents that trigger L-glutamte exocytosis such as acetylcholine did not trigger any Ca2+-dependent 5-HT release. Vice versa neither NE nor phenylephrine caused synaptic-like microvesicle-mediated L-glutamate exocytosis. These results indicated that upon stimulation of a adrenoceptors pinealocytes secrete 5-HT through a Ca2+-dependent exocytotic mechanism, which is distinct from the exocytosis of synaptic-like microvesicles.
| Original language | English |
|---|---|
| Pages (from-to) | 533-540 |
| Number of pages | 8 |
| Journal | Journal of Neurochemistry |
| Volume | 81 |
| Issue number | 3 |
| DOIs | |
| Publication status | Published - 2002 |
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Keywords
- 5-hydroxytryptamine (serotonin)
- Dense-cored vesicles
- Exocytosis
- Melatonin
- Synaptic-like microvesicle
- Vesicular monoamine transporter (VMAT)
ASJC Scopus subject areas
- Biochemistry
- Cellular and Molecular Neuroscience
Cite this
Norepinephrine triggers Ca2+-dependent exocytosis of 5-hydroxytryptamine from rat pinealocytes in culture. / Yamada, Hiroshi; Hayashi, Mitsuko; Uehara, Shunsuke; Kinoshita, Mika; Muroyama, Akiko; Watanabe, Masami; Takei, Kohji; Moriyama, Yoshinori.
In: Journal of Neurochemistry, Vol. 81, No. 3, 2002, p. 533-540.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Norepinephrine triggers Ca2+-dependent exocytosis of 5-hydroxytryptamine from rat pinealocytes in culture
AU - Yamada, Hiroshi
AU - Hayashi, Mitsuko
AU - Uehara, Shunsuke
AU - Kinoshita, Mika
AU - Muroyama, Akiko
AU - Watanabe, Masami
AU - Takei, Kohji
AU - Moriyama, Yoshinori
PY - 2002
Y1 - 2002
N2 - 5-Hydroxytraptamine (5-HT) is a precursor and a putative modulator for melatonin synthesis in mammalian pinealocytes. 5-HT is present in organelles distinct from L-glutamate containing synaptic-like microvesicles as well as in the cytoplasm of pinealocytes, and is secreted upon stimulation by norepinephrine (NE) to enhance serotonin N-acetyltransferase activity via the 5-HT2 receptor. However, the mechanism underlying the secretion of 5-HT from pinealocytes is unknown. In this study, we show that NE-evoked release of 5-HT is largely dependent on Ca2+ in rat pinealocytes in culture. Omission of Ca2+ from the medium and incubation of pineal cells with EGTA-tetraacetoxymethyl-ester inhibited by 59 and 97% the NE-evoked 5-HT release, respectively. Phenylephrine also triggered the Ca2+-dependent release of 5-HT, which was blocked by phentolamine, an α antagonist, but not by propranolol, a β antagonist. Botulinum neurotoxin type E cleaved 25 kDa synaptosomal-associated protein and inhibited by 50% of the NE-evoked 5-HT release. Bafilomycin Al, an inhibitor of vacuolar H+-ATPase, and reserpine and tetrabenazine, inhibitors of vesicular monoamine transporter, all decreased the storage of vesicular 5-HT followed by inhibition of the NE-evoked 5-HT release. Agents that trigger L-glutamte exocytosis such as acetylcholine did not trigger any Ca2+-dependent 5-HT release. Vice versa neither NE nor phenylephrine caused synaptic-like microvesicle-mediated L-glutamate exocytosis. These results indicated that upon stimulation of a adrenoceptors pinealocytes secrete 5-HT through a Ca2+-dependent exocytotic mechanism, which is distinct from the exocytosis of synaptic-like microvesicles.
AB - 5-Hydroxytraptamine (5-HT) is a precursor and a putative modulator for melatonin synthesis in mammalian pinealocytes. 5-HT is present in organelles distinct from L-glutamate containing synaptic-like microvesicles as well as in the cytoplasm of pinealocytes, and is secreted upon stimulation by norepinephrine (NE) to enhance serotonin N-acetyltransferase activity via the 5-HT2 receptor. However, the mechanism underlying the secretion of 5-HT from pinealocytes is unknown. In this study, we show that NE-evoked release of 5-HT is largely dependent on Ca2+ in rat pinealocytes in culture. Omission of Ca2+ from the medium and incubation of pineal cells with EGTA-tetraacetoxymethyl-ester inhibited by 59 and 97% the NE-evoked 5-HT release, respectively. Phenylephrine also triggered the Ca2+-dependent release of 5-HT, which was blocked by phentolamine, an α antagonist, but not by propranolol, a β antagonist. Botulinum neurotoxin type E cleaved 25 kDa synaptosomal-associated protein and inhibited by 50% of the NE-evoked 5-HT release. Bafilomycin Al, an inhibitor of vacuolar H+-ATPase, and reserpine and tetrabenazine, inhibitors of vesicular monoamine transporter, all decreased the storage of vesicular 5-HT followed by inhibition of the NE-evoked 5-HT release. Agents that trigger L-glutamte exocytosis such as acetylcholine did not trigger any Ca2+-dependent 5-HT release. Vice versa neither NE nor phenylephrine caused synaptic-like microvesicle-mediated L-glutamate exocytosis. These results indicated that upon stimulation of a adrenoceptors pinealocytes secrete 5-HT through a Ca2+-dependent exocytotic mechanism, which is distinct from the exocytosis of synaptic-like microvesicles.
KW - 5-hydroxytryptamine (serotonin)
KW - Dense-cored vesicles
KW - Exocytosis
KW - Melatonin
KW - Synaptic-like microvesicle
KW - Vesicular monoamine transporter (VMAT)
UR - http://www.scopus.com/inward/record.url?scp=0035983532&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0035983532&partnerID=8YFLogxK
U2 - 10.1046/j.1471-4159.2002.00839.x
DO - 10.1046/j.1471-4159.2002.00839.x
M3 - Article
C2 - 12065661
AN - SCOPUS:0035983532
VL - 81
SP - 533
EP - 540
JO - Journal of Neurochemistry
JF - Journal of Neurochemistry
SN - 0022-3042
IS - 3
ER -